Cellular therapy has become recognised as a new treatment modality for some diseases, particularly for diseases which are caused by loss of or damage to cells producing factors necessary for control of physiological functions. Cellular therapy holds the promise of replacing lost or damaged cells with introduced cells to improve the impaired physiological functions. For example, transplantation of islets of Langerhans cells has the potential for restoring carbohydrate control in patients with diabetes.
Cellular therapy has a variety of limitations. For example, one limiting factor is the difficulty in transplanting cells and ensuring that the transplanted cells continue to function as they would in their natural state. In addition, the introduction of non-autologous (allogeneic or xenogeneic) cells will typically elicit an immune response, requiring immunosuppressant therapy to the host as well.
For example, whilst the use of Clinical Islet Transplantation using hepatic portal vein introduction of islet cells can achieve insulin independence rates of ˜80% at 1 year, the procedure still requires multiple islet infusions over time and immunosuppressive therapy. The direct exposure of the cells to the blood may also lead to an inflammatory reaction that can destroy a significant portion of the transplanted cells and the procedure carries a significant risk of portal vein thrombosis.
An alternative approach for cellular therapy has been to deliver cells using devices that attempt to provide a biologically suitable environment for the cells to reside. However, this type of approach typically results in a rapid loss of cell function. This type of approach also suffers from a variety of other deficiencies, such as one or more of an induction of an inflammatory response when the device is introduced into the host, an incompatibility of the device with the biological milieu, difficulties in imaging the device and/or the implantation environment, difficulties with loading the device with cells, the need to surgically load (and re-load) the cells, an inability to load an appropriate number of cells for a sustained therapeutic effect, and a difficulty in removing the device if/when it needs replacement.
Accordingly, there remains a need for improved methods of cellular therapy.